1. Field of the Invention
The present invention relates to foam control compositions, their preparation and use in aqueous media. Specifically, the invention relates to a defoamer composition particularly useful in controlling foam problems encountered in low to moderate temperature pulp and paper mill process and effluent water streams.
2. Discussion of Background Information
Many waste treatment systems and industrial processes have problems caused by foam that forms as the wastewater or process water flows through the system or process. Foam can occur in any aqueous stream that contains contaminants or additives that lower the surface tension of the stream. These materials are typically organic chemicals. They may be derived from natural chemicals (e.g., lignin, humic acid, tannin), waste chemicals, water treatment chemicals, process treatment chemicals, detergents, cleaners, products or byproducts of industrial processes, microbiological byproducts, etc. The system may also contain other materials that stabilize the foam after it has formed. Such materials include polymers, surfactants, suspended organic and inorganic solids, colloidal material, proteins, and microbiological organisms.
Foam problems frequently occur when a wastewater or process water stream is subjected to a unit operation that increases the total area of the system""s gas/liquid interfaces. Such an increase occurs whenever a liquid is broken up into droplets or a gas is introduced into a liquid. Processes causing these effects include: mechanical processes (e.g., agitation, mixing, turbulent flow, pumping, aeration, gasification, reduction in pressure, increase in temperature), biological processes (e.g., fermentation, anaerobic digestion), and chemical processes (e.g., oxidation, recarbonation, gasification, distillation, solvent stripping, and reactions generating gas).
Foam in wastewater or process water is a problem for several reasons and can be detrimental to system processes (e.g., pumping, mixing, distillation, chemical reaction, heat transfer, evaporation, sedimentation, etc.). Foam can interfere with system sensors and controllers (e.g., level controllers, pH sensors, temperature sensors) and can adversely affect the quality and throughput of a product (e.g., holes in paper, and poor adhesion of coatings). Foam can also be a safety or health hazard (e.g., airborne bacteria, and tank overflows) or can also be an aesthetic problem, (e.g., foamy discharge to receiving streams).
The pulp and paper industry experiences some of the most troublesome foam problems because of the ubiquitous presence of lignins and other foam-causing materials. Foaming frequently occurs in pulp washing, pulp screening, pulp bleaching, and waste treatment processes. In addition to the visible foam that occurs on the surface of process and effluent streams, foam may also occur below the surface in the form of entrained air bubbles, particularly in aqueous streams that contain fibers and other particulates. Air bubbles become entrained when they cannot rise to the surface by normal buoyant forces because they are adsorbed to the particulate materials in the stream or their motion is impeded by the presence of the particulates. Entrained air bubbles are a problem because they inhibit the drainage of the washing liquor through the fiber mat which in turn slows down production. Entrained air bubbles are also known to impair paper formation and tensile strength.
The invention relates to defoaming agent compositions for controlling foam, i.e., defoaming or inhibiting the formation of foam, in aqueous environments, particularly in wastewater systems and aqueous industrial process systems.
The invention also relates to methods for controlling foam, i.e., defoaming or inhibiting the formation thereof, in aqueous environments, particularly in wastewater systems and in aqueous industrial process systems by adding to the system an effective amount of defoaming components, such as by adding the defoaming agent composition of the present invention.
In one aspect, the invention is directed to a method of at least one of defoaming an aqueous system and inhibiting the formation of foam in an aqueous system comprising adding to the aqueous system an effective amount of primary alcohol component that is solid at 25xc2x0 C., alcohol alkoxylate component and emulsifier component to at least one of defoam the aqueous system and inhibit formation of foam in the aqueous system.
In another aspect, the present invention is directed to a stable defoamer composition comprising primary alcohol component that is solid at 25xc2x0 C., alcohol alkoxylate component, emulsifier component and water.
The primary alcohol component can comprise at least one linear primary alcohol, and the at least one linear primary alcohol can comprise mixtures of primary linear alcohols. The mixture of primary linear alcohols can comprise C14 to C32 primary linear alcohols, more preferably C18 to C32 primary linear alcohols, and even more preferably C18 to C30 primary linear alcohols. Preferably, at least about 35 percent of the primary linear alcohols comprise C20 to C26 primary linear alcohols, more preferably at least about 70 percent of the primary linear alcohols comprise C20 to C26 primary linear alcohols, and even more preferably at least about 80 percent of the primary linear alcohols comprise C20 to C26 primary linear alcohols.
The primary alcohol component can have a melting point of at least about 40xc2x0 C.
The primary alcohol can comprise at least one of fatty alcohols comprising at least one of palmityl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, ceryl alcohol, montanyl alcohol, myricyl alcohol, melissyl alcohol, lacceryl alcohol and geddyl alcohol, and synthetic higher aliphatic alcohols comprising at least one of 1-hexadecanol, 1-octadecanol, 1-eicosanol, 1-docosanol, 1-tetracosanol, 1-hexacosanol, 1-octacosanol, 1-triacontanol, 1-dotriacontanol and 1-tetratriacontanol.
The alcohol alkoxylate component can comprise C12 to C18 alcohol alkoxylates, preferably C12 to C18 alcohol alkoxylates containing ethylene oxide groups and propylene oxide groups.
The alcohol alkoxylate component can have a cloud point of at least 16xc2x0 C., with one cloud point range being about 20xc2x0 C. to 38xc2x0 C., and another cloud point range being about 22xc2x0 C. to 25xc2x0 C.
The alcohol alkoxylate component can have a molecular weight of at least about 630, more preferably about 630 to 3,000, and even more preferably about 1,200 to 3,000.
The emulsifier component can comprise at least one nonionic surfactant, and can additionally comprise at least one anionic surfactant.
At least one branched alcohol can be added. Moreover, at least one of stabilizing and thickening agents can be added.
The primary alcohol component, the alcohol alkoxylate component and the emulsifier component can be added by adding an aqueous defoaming composition to the aqueous system. The aqueous defoaming composition can comprise about 10 to 35 weight percent primary alcohol, about 2 to 12 weight percent alcohol alkoxylate, and about 0.2 to about 5 weight percent of emulsifier component.
The emulsifier component can comprise up to about 1.0 weight percent of at least one anionic surfactant, and from about 0.2 to 5.0 weight percent of at least one nonionic surfactant. The at least one nonionic surfactant can comprise at least one alcohol ethoxylate. Moreover, the emulsifier component can comprise at least one water soluble alcohol ethoxylate and at least one water insoluble alcohol ethoxylate.
The aqueous system can be, for example, a papermaking system.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure.
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to describe the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
Unless otherwise stated, all percentages, parts, ratios, etc., are by weight. Moreover, unless otherwise stated, percent measurements in this application are measured by weight based upon 100% of a given sample weight. Thus, for example, 30% represents 30 weight parts out of every 100 weight parts of the sample.
Unless otherwise stated, a reference to a compound or component includes the compound or component by itself, as well as in combination with other compounds or components, such as mixtures of compounds.
Further, when an amount, concentration, or other value or parameter, is given as a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of an upper preferred value and a lower preferred value, regardless whether ranges are separately disclosed.
A significant improvement in the control of foaming in aqueous process and effluent streams can be accomplished by the use of a foam control composition, which is the subject of the present invention. The primary focus of this composition is the enhanced foam control efficacy resulting from the combination of a primary alcohol component and an alcohol alkoxylate component. The use of these two materials in combination enables an unexpected increase in both defoaming and inhibition of formation of foam as compared to conventional compositions.
The invention also relates to methods for controlling foam, i.e., defoaming and/or inhibiting the formation thereof, in aqueous environments, particularly in wastewater systems and in aqueous industrial process systems, by adding to the system a defoaming agent composition which includes a primary alcohol component and an alcohol alkoxylate component.
The primary alcohol component useful in this invention includes any primary alcohol that is solid at room temperature, i.e., 25xc2x0 C. Preferably, the primary alcohol component comprises at least one linear primary alcohol, and preferably comprises mixtures of primary linear alcohols. Even more preferably, the linear primary alcohols comprise C14 to C32 primary linear alcohols, more preferably C18 to C32 primary linear alcohols, and even more preferably C18 to C30 primary linear alcohols.
When the primary alcohol component comprises a mixture of primary linear alcohols, it is preferred that at least about 35 percent of the primary linear alcohols comprise C20 to C26 primary linear alcohols, more preferably at least about 70 percent of the primary linear alcohols comprise C20 to C26 primary linear alcohols, and even more preferably at least about 80 percent of the primary linear alcohols comprises C20 to C26 primary linear alcohols.
Preferably, the primary alcohol component has a melting point of at least about 40xc2x0 C. Thus, for example, when the primary alcohol component comprises a mixture of primary linear alcohols, the mixture will have a preferred melting point of at least about 40xc2x0 C.
Primary alcohols according to the present invention include, but are not limited to, those described in U.S. Pat. Nos. 4,340,500 and 5,679,286, which are incorporated by reference herein in their entirety.
Alcohols suitable for the purpose of this invention may be known in industry as xe2x80x9cfatty alcoholsxe2x80x9d, if they are derived from natural oleochemical source materials, or as xe2x80x9csynthetic higher aliphatic alcoholsxe2x80x9d, if they are derived from petrochemical source materials. Examples of fatty alcohols suitable for the purposes of this invention include, but are not limited to, palmityl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, ceryl alcohol, montanyl alcohol, myricyl alcohol, melissyl alcohol, lacceryl alcohol and geddyl alcohol, as well as mixtures thereof Suitable synthetic higher aliphatic alcohols include, but are not limited to, those made by the Oxo process and those made by the Ziegler process. Examples of synthetic higher aliphatic alcohols suitable for the purposes of this invention include, but are not limited to, 1-hexadecanol, 1-octadecanol, 1-eicosanol, 1-docosanol, 1-tetracosanol, 1-hexacosanol, 1-octacosanol, 1-triacontanol, 1-dotriacontanol and 1-tetratriacontanol, as well as mixtures thereof. The preferred compounds for the primary linear alcohol component are synthetic higher aliphatic alcohols having from about 14 to about 32 carbon atoms, preferably those having from 18 to 32 carbon atoms, and most preferably those having from about 18 to about 30 carbon atoms.
Commercial examples of the preferred linear primary alcohol component include, but are not limited to, Alfol 20+ (manufactured by Condea-Vista, Houston, Tex.), Nafol 20+, Nafol 20+A, Nafol 22+ and Nafol 2022 (all manufactured by Condea Chemie, Brunnsbutel, Germany), and Epal 20+ (manufactured by Amoco Chemicals, Chicago, Ill.). The preferred linear primary alcohol component may be commercially described as the still bottom product of C12 through C18 alcohol manufacturing production. As such this component may contain impurities such as C22 to C40 hydrocarbons in concentrations of about 25-40 percent by weight. The presence of such impurities does not prevent the composition from controlling foam.
The alcohol alkoxylate component according to the present invention can comprise one or more alcohol alkoxylates which function with the primary alcohol component to enable defoaming and/or the inhibition of the formation of foam. The alcohol alkoxylates of the present invention can include combinations of alkoxylates that add both hydrophobic and hydrophilic groups to the alcohol alkoxylate. For example, the alcohol alkoxylates preferably at least include ethylene oxide groups, which comprise the hydrophilic groups, and propylene oxide groups, which comprise the hydrophobic groups. The alcohol alkoxylate also contains a linear or branched alkyl chain containing 12 to 18 carbons. This alkyl chain is also a hydrophobic group. The alcohol alkoxylate preferably has a larger proportion of hydrophobic groups, such as but not limited to the propylene oxide groups, so that The alcohol alkoxylate can be considered to have an overall hydrophobic characteristic even though the alcohol alkoxylate contains hydrophilic and hydrophobic groups.
Preferably, the alcohol alkoxylates comprise C12 to C18 alcohol alkoxylates, with one preferred range being C12 to C14, and another preferred range being C14 to C18. More preferably the alcohol alkoxylates comprise C12 to C18 alcohol alkoxylates containing ethylene oxide groups and propylene oxide groups, with one preferred range being C12 to C14, and another preferred range being C14 to C18. Preferably, the alcohol alkoxylates have a cloud point of at least 16xc2x0 C., with one preferred range being about 20xc2x0 C. to about 38xc2x0 C., and another preferred range being about 22xc2x0 C. to 25xc2x0 C. Preferably, the alcohol alkoxylate has a molecular weight of at least 630, with preferred ranges being about 630 to 3,000, and about 1,200 to 3,000.
Alcohol alkoxylates useful in the present invention include, but are not limited to, C12 to C18 alcohol alkoxylates such as disclosed in U.S. Pat. Nos. 5,562,862 and 5,460,698, whose disclosures are incorporated by reference herein in their entireties. These C12 to C18 alcohol alkoxylates may include fatty alcohol ethoxylate/propoxylates which have a cloud point of at least 16xc2x0 C., preferably about 22xc2x0 C. to about 25xc2x0 C., and a molecular weight of from about 1,200 to about 3,000. The fatty alcohol ethoxylate/propoxylates have a chemical structure represented by the following formula: 
where R is linear or branched chain alkyl having from about 12 to about 18 carbon atoms, preferably a C14 to C18 mixture; x is from about 2 to about 20; and y is from about 1 to about 40.
Also suitable as the alcohol alkoxylate component of the present invention are secondary alcohol ethoxylate/propoxylates which have a cloud point of about 20xc2x0 C. to about 38xc2x0 C. and a molecular weight of at least 630. These materials have a chemical structure represented by the following formula:
Rxe2x80x94O(CH2CH2O)x[CH2CH2O/CH2CH(CH3)O]yCH2CH(CH3)OH
where R is linear or branched chain alkyl having from about 11 to about 15 carbon atoms, preferably a C11 to C15 or C12 to C14 mixture; x is from about 1 to about 6; y is from about 1 to about 3.
Examples of preferred alcohol alkoxylate component include ethoxylated/propoxylated alcohols manufactured by Deforest Enterprises (Boca Raton, Fla.), such as Delonic LF-EP; Harcros Chemicals, Inc. (Kansas City, Kans.), such as T-Det LF-416; Henkel Corp. (Cincinnati, Ohio), such as Dehypon LS-54 and Dehypon LS-45; Huntsman Chemical, (Houston, Tex.), such as the Surfonic alcohol alkoxylates, including Surfonic LF-27, Surfonic LF-47 and Surfonic LF-50; Rhodia, Inc. (Cranbury, N.J.), such as, Antarox LF-224 and Antarox BL; and Union Carbide (Danbury, Conn.), such as the Tergitol Minifoams alcohol alkoxylates, including Tergitol Minifoam 1X and Tergitol Minifoam 2X.
The composition according to the present invention also includes an emulsifying agent component. The emulsifying agent component can comprise one or more of any emulsifier capable of dispersing the primary alcohol component and the alcohol alkoxylate into aqueous media. The at least one emulsifying agent component can be present at any concentration that enables the dispersion of the components into the aqueous media. Preferably, the concentration of the emulsifying agent component is from about 0.2 to 5.0 weight percent, more preferably, the concentration of the emulsifying agent component is from about 0.5 to 3 weight percent.
The emulsifying agent component preferably comprises at least one nonionic surfactant. The nonionic surfactant that can be used in the emulsifying agent component of the present invention can include, but is not limited to, alcohol ethoxylates, fatty acid ethoxylates, alkyl phenol ethoxylates, sorbitan esters, sorbitan ester ethoxylates, ethylene oxide/propylene oxide copolymers, glycol esters, glyceryl esters, polyglycerides and polyoxyalkylene glyceride esters. A preferred nonionic surfactant is alcohol ethoxylate, such as Tergitol 15-S series (Manufactured by Union Carbide, Danbury, Conn.), Neodol 23-series and Neodol 25-series (manufactured by Shell Chemicals, Houston, Tex.), Macol LA-series (manufactured by BASF Corp., Mt. Olive, N.J.), Makon TD-series (manufactured by Stepan Co., Northfield, Ill.), Surfonic L-series (manufactured by Huntsman Chemical, Houston, Tex.), Tomadol 25-series (manufactured by Tomah Products Inc., Reserve, La.), Alfonic 1216-series and Alfonic 1416-series (manufactured by Condea-Vista, Houston, Tex.). It is noted that the nonionic surfactant can be water soluble and/or water insoluble, such as water soluble and water insoluble alcohol ethoxylates.
The emulsifying agent component of the present invention can also include anionic surfactants which include, but are not limited to, alcohol sulfates; alkylaryl sulfonates; alkyl benzene sulfonates: ethoxylated alcohol sulfates; sulfates and sulfonates of ethoxylated alkyl phenols; sulfates of fatty esters; sulfates and sulfonates of alkyl phenols; sulfonates of condensed naphthalenes; sulfonates of naphthalene; sodium derivatives of sulfo-succinates; alkali salts of petroleum sulfonates; alkali phosphate esters and the like. Preferred anionic surfactants include sodium dodecylbenzene sulfonate, triethanolamine dodecylbenzene sulfonate, and sodium dioctyl sulfosuccinate. The anionic surfactant may be present in the subject defoamer composition at a concentration from 0 to about 1 weight percent of the total composition.
Thus, the emulsifying agent component preferably comprises at least one nonionic surfactant, and can contain at least one anionic surfactant in combination with the at least one nonionic surfactant.
The composition preferably includes from about 10 to about 35 weight percent primary alcohol, from about 2 to about 12 weight percent alcohol alkoxylate, and from about 0.2 to about 5 weight percent of at least one emulsifying agent component, and the balance being water.
Still further, the composition according to the present invention can also contain other additives, such as additives conventionally incorporated into defoaming compositions.
For example, the composition according to the present invention can contain branched alcohol, such as, but not limited to, 2-ethyl-1-hexanol, 2 butyl-octanol, 2-hexyl-decanol, 2-octyl-dodecanol, 2-decyl-tetradecanol. Branched alcohols can be present in the composition in varying amounts, preferably from 0 to about 2 percent by weight, more preferably up to about 1.1 percent by weight.
Stabilizing and/or thickening agents can also be added to the composition according to the present invention in order to prevent phase separation of the composition during storage. Stabilizing/thickening agents suitable for use in the present invention include, but are not limited to, xanthan gum, poly(acrylic acid), high molecular weight polyacrylates, naturally derived gums, carboxymethyl cellulose, hydroxyethyl cellulose, hectorite clay and the like. The stabilizing/thickening agent can be present in the defoamer composition at varying concentrations, preferably from 0 to about 2 percent by weight. A preferred stabilizer/thickening agent is xanthan gum.
When a stabilizing/thickening agent is included in the composition, an alkaline material may be added as recommended by the manufacturer of the stabilizing/thickening agent to facilitate hydration thereof. Examples of alkaline materials suitable for this purpose includesodium hydroxide, ammonium hydroxide, triethanola
The composition according to the present invention may also contain at least one preservative to prevent or inhibit microbiological activity during product storage. Suitable preservatives include, but are not limited to, benzisothiazolinone, glutaraldehyde, methyl paraben, propyl paraben, isothiazolinone, and mixtures thereof. The preservative can be present in the defoamer composition at varying concentrations, preferably from 0 to about 0.1 weight percent. A preferred preservative is Proxel GXL (1,2-benzisothiazolin-3-one) manufactured by Zeneca, Wilmington, Del.
The defoaming agent composition of the present invention is suitable for defoaming or inhibiting the formation of foam in a wide variety of aqueous systems; however, it has been found that such a defoaming agent has particular applicability to the pulp and paper industry and the textile industry and is especially useful for controlling foam in process waters and wastewater effluents from these industries. The defoaming agent composition of the present invention can be added to the aqueous system in an effective amount to destroy existing foam and/or inhibit the formation of new foam, generally being added in an amount to provide at least 1 part by volume of defoaming agent per million parts by volume of aqueous system liquid. In general, no added beneficial effect is obtained by the use of amounts greater than 500 parts by volume of defoaming agent per million parts of aqueous system liquid. It is to be understood that the specific amount to be employed will vary with each system, and the selection of an optimum amount is deemed to be within the scope of those skilled in the art; however, it is noted that a preferred range is about 5 to 100 parts by volume defoaming agent per million parts of aqueous system liquid.